[2] Kasztner was one of the leaders of the Budapest Aid and Rescue Committee (Va'adat Ezrah Vehatzalah, or Vaada), which smuggled Jewish refugees into Hungary during World War II.

Kasztner negotiated with Adolf Eichmann, a senior SS officer and mastermind of the Holocaust, to allow 1,684[3] Jews to leave instead for Switzerland on what became known as the Kastner train, in exchange for money, gold, and diamonds.

[6] Kasztner was shot on March 3, 1957, by Zeev Eckstein, part of a three-man squad from a group of veterans from the pre-state militia Lehi led by Yosef Menkes and Yaakov Heruti, and died of his injuries 12 days later.

[7] The Supreme Court of Israel overturned two of the charges against Kasztner in January 1958 in a 4–1 decision, finding that he had tried to negotiate the release of as many people as he could and had acted on the assumption that it would cause more harm than good to tell the Jews bound for Auschwitz of the mass murders taking place there.

Kasztner was raised with his two brothers in a two-story brick house in the southern part of the city by his father, Yitzhak, a merchant and a devout man who spent most of his day in the synagogue, and his mother, Helen, who ran the family store.

[8] Anna Porter writes that he became known for his good looks, sharp mind, quick wit, and his intense focus, as a result of which his mother decided that he should study law, though his heart was in politics.

The law limited Jewish university enrollment to 6%, reflecting Jews' portion of the population, and although Kolozsvár became part of Romania shortly after, and the legislation itself was allowed to lapse eight years later in Hungary, it affected Kasztner's teenage political orientation, and he decided at the age of 15 to become a Zionist.

[15] As the German army moved across Europe, Kasztner set up an information center in Cluj to help refugees arriving from Austria, Poland, and Slovakia.

His main concern was to provide Jewish refugees with safe passage, using his ability to bribe and charm to obtain exit visas from the Romanian government.

He wanted to continue his work helping Jewish refugees in Kolozsvár, and with that in mind, had obtained a letter of introduction from József Fischer to Ottó Komoly, an engineer and president of the Budapest Zionist Association.

Porter writes that Kasztner had to wait in line for two hours at the Agency's office on Erzsébet Boulevard, among scores of Jewish refugees desperate to find a way to escape to Palestine.

Komoly continued to introduce Kasztner to key figures in the Budapest Zionist movement, one of whom was Sam Springmann, who was bribing officials – in part with money from the Jewish Agency – to carry messages and food parcels into Łódź and other ghettos in Poland.

[citation needed] During the summer of 1944, Kasztner repeatedly met with Adolf Eichmann, who was in charge of deporting Hungary's 800,000-strong Jewish community to Auschwitz in occupied Poland.

They included the Rabbi Joel Teitelbaum, the writer Béla Zsolt, the psychiatrist Leopold Szondi, the opera singer Dezső Ernster, the artist István Irsai, and other intellectuals, scientists, religious leaders, and political activists, but also people who were neither rich nor prominent, not least a group of Polish orphans.

Professor Eli Reichenthal wrote that Kasztner at that stage was actually being blackmailed by the Germans, as his parents, friends and close family were all on the "Kastner train" stranded in the Bergen-Belsen concentration camp.

[25] Hoocaust historian Prof. David Kranzler stated that Kasztner implored George Mantello (Mandel), then First Secretary of El Salvador in Switzerland, not to publicize content of the report.

"[27] While negotiations about the first train were continuing, three Jewish Special Operations Executive members from Palestine, Hannah Szenes and two men, Yoel Palgi and Peretz Goldstein, were parachuted into Yugoslavia and attempted to penetrate the Hungarian border.

[citation needed] Shmuel Tamir, Gruenwald's attorney, claimed that this was one of the main reasons that he felt that Kasztner had been nothing more than a German collaborator, to save his family and perhaps for money.

[citation needed] The report was later released to the leaders of Jewish organizations in Budapest and elsewhere in the hope that Hungarian Jews would be warned that they were being deported to a death camp and were not being resettled, as they had been led to believe.

[28] George Mantello (Mandel), an Orthodox Jew from Hungary and first secretary of the El Salvador mission to Switzerland, sent a Romanian diplomat friend, Florian Manoliu, to find out what was happening to his family, who by then had been murdered.

The resulting international outcry, including warnings to Hungary's ruler Miklós Horthy by Roosevelt and Churchill, was one of the main reasons that the Hungarian government stopped the deportations.

Löb argued, "With no access to the media and limited opportunities to travel, under constant observation by German and Hungarian secret police, he could hardly have raised the alarm in an effective way" and even if he had, the Jews, "surrounded by enemies, stripped of their rights and possessions, having neither the arms nor the experience", were unable to organise either resistance or mass escapes.

Himmler had ordered Becher to attempt to stop further exterminations at the concentration camps as the Allies gained further ground in the closing days of World War II.

Kasztner intervened on his behalf and sent an affidavit to his de-Nazification hearing, stating that "[Becher is] cut from a different wood than the professional mass murderers of the political SS".

It is likely that he did so with the knowledge and support of the Jewish Agency (Sochnut, Zionist leadership in Palestine, the Yishuv), from which he received a refund for expenses related to his trip to Nuremberg.

It is theorized that this was done in the hope of obtaining help to recover stolen Jewish assets for Israel, receiving hidden weapons and capturing Eichmann in return.

An American lawyer attached to the Nuremberg Trials wrote that there was a relief when Kaszter returned to Palestine, since he was constantly in POW camps looking for more and more Nazis to rescue.

[42]The Israeli government's decision to appeal on Kasztner's behalf led to its collapse, as Prime Minister Moshe Sharett resigned when the General Zionists, a member of his coalition, refused to abstain from voting on a no-confidence motion filed by Herut and Maki.

About an hour after the shooting, Shin Bet (Israel's internal security service) opened an investigation, focusing its efforts on the Lehi veterans group led by Menkes and Heruti.

[49] The idea that the killing was a government conspiracy has been described by Elliott Jager as "absolute nonsense", because the head of the intelligence service was a close personal friend of Kasztner.